Re: [Anima] [lamps] Long-lived certificates, but frequently renewed certificates

Eliot Lear <> Tue, 23 March 2021 06:47 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id C27E33A1FCA; Mon, 22 Mar 2021 23:47:05 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -7.948
X-Spam-Status: No, score=-7.948 tagged_above=-999 required=5 tests=[DKIMWL_WL_HIGH=-0.251, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HTML_MESSAGE=0.001, SPF_NONE=0.001, URIBL_BLOCKED=0.001, USER_IN_DEF_DKIM_WL=-7.5] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (1024-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id bQ2ca2mcHLuH; Mon, 22 Mar 2021 23:47:00 -0700 (PDT)
Received: from ( []) (using TLSv1.2 with cipher DHE-RSA-SEED-SHA (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 3AFAC3A1FC8; Mon, 22 Mar 2021 23:47:00 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple;;; l=8792; q=dns/txt; s=iport; t=1616482020; x=1617691620; h=from:message-id:mime-version:subject:date:in-reply-to:cc: to:references; bh=i0H9vIy//I1Z5Z8z0wtNqfbUKnm5UEtjP0BPU+XtO8Y=; b=K1GZnlXu+kuSm4g9jKnHwJQat1mawtYl0EUKyZ2s8AkbTRZZimP5dXDr ETEp9W5Ms74VAL/+YOjTI07hHIprbRpvfqa/sfsDsxLJHdgMaqC3dHejA +nKROcGzEJaWw+gOECNpJYu2cwXATRL6XUJ56LIoyOiCGDnf/MIjQCDpa c=;
X-Files: signature.asc : 488
IronPort-HdrOrdr: A9a23:FBOxGqsCw1ictGkHAgwphhPZ7skD9NV00zAX/kB9WHVpW+aT/v re/8gz/xnylToXRTUcicmNUZPtfVrw/YN4iLNxAZ6MRw/j0VHDEKhD6s/YzyTkC2nC8IdmtZ tIV6RlEtX/ARxbgK/BjTWQN9YlzJ25/LuzheHYpk0DcShQZ6tt7xh0B2+geyUceCB8CZU0D5 aa7MZczgDQHEg/VNixBXUOQoH4yeHjqZSOW29lOzcXrC2HjTal89fBYnyl9yZbdS9TyrE/9m WAtAr16syYwpeG4y6Z8XPP5JJLn9ak8P9/PYinj8gYLSiEsHfOWLhc
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-AV: E=Sophos;i="5.81,271,1610409600"; d="asc'?scan'208,217";a="34415305"
Received: from (HELO ([]) by with ESMTP/TLS/DHE-RSA-SEED-SHA; 23 Mar 2021 06:46:55 +0000
Received: from [] ([]) by (8.15.2/8.15.2) with ESMTPS id 12N6ksd2032728 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Tue, 23 Mar 2021 06:46:55 GMT
From: Eliot Lear <>
Message-Id: <>
Content-Type: multipart/signed; boundary="Apple-Mail=_8AC6219A-5E57-4EE2-BBD5-6333DA461BDC"; protocol="application/pgp-signature"; micalg=pgp-sha256
Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.\))
Date: Tue, 23 Mar 2021 07:46:53 +0100
In-Reply-To: <20210322212842.GS30153@localhost>
Cc: Michael Richardson <>, Toerless Eckert <>, LAMPS <>,
To: Nico Williams <>
References: <> <20210318183001.GN30153@localhost> <2113.1616093888@localhost> <> <20210320203655.GR30153@localhost> <> <20210322212842.GS30153@localhost>
X-Mailer: Apple Mail (2.3654.
X-Outbound-SMTP-Client:, []
Archived-At: <>
Subject: Re: [Anima] [lamps] Long-lived certificates, but frequently renewed certificates
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Autonomic Networking Integrated Model and Approach <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Tue, 23 Mar 2021 06:47:06 -0000

> On 22 Mar 2021, at 22:28, Nico Williams <> wrote:
> End entities send a validation chain for their EE certs, but not the
> root CA's cert, and anyways, RPs need to know trust anchors a priori.
> Therefore rolling out new TAs is tricky.

The presumption we make in the enterprise is that distribution of TAs in services happens as a matter of normal system management.  Absent those TAs the service is going to experience a whole lot of failures.  At the application level beyond the bounds of the enterprise, this is a different matter, to be sure.

> TA rollover needs a device update protocol.

Within the bounds of the enterprise, that’s EST (RFC 7030).  See Section 4.1.2 “/cacerts”.  This delivers a PKCS#7 pack of certs.  RFC 8951 modestly amends that.

> (Speaking of uniformResourceIdentifier type issuerAltNames, what are
> their semantics?  If RFC5280 covers that, I've missed it.)

Good question.

>> The LDevID change out is harder.  A device can have many trust
>> anchors, but the LDevID change-out has to be handled a bit more
>> carefully.
>> [...]
> Yes, devices can have considerations that an EST server may not be able
> to know.
> So I think we're talking about the server indicating a refreshAfter time
> or a doNotRefreshBefore time rather than a refreshAt time.  An
> informative "you can refresh after this $time" and maybe a normative "do
> not even think of refreshing before this $time".

That covers one case.  Another case that has to be covered is when there’s a need for an unscheduled rollover.  This might happen if there was some concern that a private key has been compromised.  And then...

> That said, a simple certificate refresh where no algorithms change, no
> parameters change, no critical extensions are added, etc. -- where the
> only real change is the validity period -- surely this is safe to
> perform whenever the device can talk to the online CA.  One could argue
> that making sure that the only change is the validity period (and maybe
> the SPKI, but not its alg or params) is difficult to ensure.  Michael
> tells me maybe the CA software gets upgraded and other changes sneak in
> that one did not expect.

Well, and we haven’t even begun to discuss secure time stamps here (you can track some recent discussion of that discussion on the openssl-users list).  And you’re hitting another issue- stuff like RFC 4476.  I don’t know how widely that extension is found, but there are others; and there is something of a debate in some circles about whether to do RBAC et al in certs.

And so an occasional query also seems appropriate.  EST doesn’t really define that.